Embossed plate external oil cooler

ABSTRACT

An oil cooler includes an oil guiding arrangement an oil guiding arrangement and an air guiding arrangement. The oil guiding arrangement has an oil inlet, an oil outlet, and a plurality of oil passageways communicatively between the oil inlet and the outlet and spacedly being stacked apart from each other. The air guiding arrangement has a plurality of air guiding passageways alternating with the oil passageways and arranged for guiding air flowing through the air guiding passageways to heat exchange with the oil so as to cool down the oil before exiting at the oil outlet. A plurality of embossed plates are disposed in the oil passageways respectively for creating a three-dimensional oil movement within the oil passageway to heat exchange with the air, so as to enhance the heat exchange efficiency.

BACKGROUND OF THE PRESENT INVENTION

1. Field of Invention

The present invention relates to an oil cooler, and more particularly to an external oil cooler having an embossed plate in the oil chamber to increase the heat exchange efficiency.

2. Description of Related Arts

Oil cooler is a heat exchanger which uses a medium with lower temperature to exchange heat with the oil. Accordingly, the medium is preferably air, and the oil is intended to include engine oils, transmission fluids, hydraulic fluids, or other fluid.

The oil is cycling within an enclosed loop. In a portion of the loop, the fresh air contacts with the outer wall of the loop. Since the temperature of the fresh air is lower than the temperature of the oil, heat exchange happens between the fresh air and the oil through the wall of the loop. The heat is carried away by the fresh air, and the oil is cooled.

In order to increase the efficiency of heat exchanging, it is necessary to maximize the area of the wall of the loop between the air and the oil. In U.S. Pat. No. 5,036,911, an oil cooler is disclosed which comprises a plurality of stacked plate pairs. Each stacked plate pair forms a channel for the oil to pass through. Between the stacked plate pares are louvered fins to contact with the air. The louvered fins act as the extension of the wall of the channel, which increases the contact area between the air and the wall of the channel.

On the other hand, in order to increase the contact area between the oil and the wall of the channel, the wall of the channel also comprises a plurality of projection protruding towards the inner space of the channel. These projections also increase the contact area between the oil and the channel.

Although the projection design largely increased the contact area and increased the heat exchange efficiency, it still can be improved. The projection design increased the contact area but also occupied the inner space of the channel; therefore less oil can flow through. To guarantee the flow rate of the oil, more channels are needed with will increase the weight and size of the cooler. Also, since the projections are formed on the plate which acts as the wall of the channel, it limits the shape, dimension, and number of the projection. More complex projections are difficult to form.

Therefore, the present invention provides a solution to improve the structure of the oil cooler.

SUMMARY OF THE PRESENT INVENTION

The invention is advantageous in that it provides an oil cooler having an embossed plate to increase the heat exchange efficiency.

Another advantage of the invention is to provide an oil cooler using an embossed plate to increase the contact area between the oil and the wall of the oil channel.

Another advantage of the invention is to provide an oil cooler having an embossed plate which saves the space and weight.

Another advantage of the invention is to provide an oil cooler which is easy to fabricate and assemble.

Additional advantages and features of the invention will become apparent from the description which follows, and may be realized by means of the instrumentalities and combinations particular point out in the appended claims.

According to the present invention, the foregoing and other objects and advantages are attained by providing an oil cooler, comprising:

-   -   an oil guiding arrangement having an oil inlet, an oil outlet,         and a plurality of oil passageways communicatively between the         oil inlet and the outlet for guiding oil longitudinally flowing         from the oil inlet to the oil outlet, wherein the oil         passageways are spacedly stacked apart from each other;     -   an air guiding arrangement having a plurality of air guiding         passageways alternating with the oil passageways and arranged         for guiding air flowing through the air guiding passageways to         heat exchange with the oil so as to cool down the oil before         exiting at the oil outlet; and     -   a plurality of embossed plates disposed in the oil passageways         respectively, wherein each of the embossed plates has an upper         side, a bottom side, and a plurality of guiding elements         protruding from the upper and bottom sides in an alternating         manner in such a manner that when the oil flow passes through         the oil passageway, the oil flow is guided to flow between the         upper side and the bottom side, to transversely flow at the         embossed plate, and to longitudinally flow at the embossed plate         from the oil inlet to the oil outlet, so as to create a         three-dimensional oil movement within the oil passageway to heat         exchange with the air.

Still further objects and advantages will become apparent from a consideration of the ensuing description and drawings.

These and other objectives, features, and advantages of the present invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional perspective view of an oil cooler according to a preferred embodiment of the present invention.

FIG. 2 is a sectional perspective view of the oil cooler according to the above preferred embodiment of the present invention.

FIG. 3 is a sectional view of an embossed plate of the oil cooler according to the above preferred embodiment of the present invention.

FIG. 4 illustrates an alternative mode of the embossed plate of the oil cooler according to the above preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 to 3 of the drawings, an oil cooler for exchanging heat with oil according to a preferred embodiment of the present invention is illustrated, wherein the oil cooler comprises and oil guiding arrangement 10 for guiding oil flowing from an oil inlet 11 to an oil outlet 12, and an air guiding arrangement 20 for guiding a medium, preferably fresh air, to exchange heat between the oil and the air of the medium, so as to cool down the oil before the oil existing the oil outlet 12.

The oil guiding arrangement 10 further comprises a plurality of oil passageways 13 communicatively extending from the oil inlet 11 to the oil outlet 12 of the oil guiding arrangement 10. The oil passageways 13 are preferably to be spacedly stacked with each other, so that the oil is guided to longitudinally flow from the oil inlet 11 to the oil outlet 12. In particularly, the oil passageways 13 are parallel with each other.

The air guiding arrangement 20 comprises a plurality of air guiding passageways 21 alternating with the oil passageways 13 and being arranged to guide the air passing therethrough for heat exchanging with the oil, so as to cool down the oil before the oil exiting the oil outlet 12. In other words, each of the air guiding passageways 21 are preferably being stacked between two corresponding oil passageways 13 for optimizing the efficiency of heat exchange between the air and the oil.

According to the preferred embodiment, in order to further enhance the heat exchanging rate between the air and the oil, the oil cooler further comprises a plurality of embossed plates 30 preferably disposed within the oil passageways 13 respectively for guiding the oil passing therethrough in a three dimensional oil movement, such that a traveling distance of the oil within the oil passageways 13 is increased to prolong a traveling time of the oil so as to effectively enhance the heat transfer rate between the oil and the medium of air.

As shown in FIG. 3, each of the embossed plates 30 has an upper side 31, a bottom side 32, and a plurality of guiding elements 33, wherein the guiding elements 33 are protruding at the upper side 31 and the bottom side 32 in an alternating manner. When the oil is passing through the oil passageways 13, the oil is guided to flow between the upper side 31 and the bottom side 32 via the guiding elements 33, i.e. the z-axis of the embossed plate 30. The oil will also be guided to transversely pass through the oil passageways 13, i.e. the y-axis of the embossed plate 30. The oil will also be guided to longitudinally flow from the oil inlet 11 to the oil outlet 12 within the elongated oil passageways 13, i.e. the x-axis of the embossed plate 30. As a result, the three dimensional oil movements within the oil passageways 13 are created by the guiding elements 33 of the embossed plates 30, so as to enhance the heat exchanging rate to effectively cool down the oil.

As best shown in FIG. 3 of the drawings, each of the embossed plates 30 has a plurality of longitudinal portions 34 longitudinally extended from one end of the embossed plate 30 to the other end thereof. The oil is guided to enter from one end to the other end of the embossed plate 30 to exit each of the oil passageways 13. Each of the longitudinal portions 34 are preferably formed a continuously square waveform structure, so that the longitudinal portion 34 has a configuration of waveform to form a wavy longitudinal cross section at each of the embossed plates 30. On the other hands, the guiding elements 33 are alignedly formed along each of the longitudinal portions 34 of the embossed plates 30 to form the waveform of the continuously square waveform structure of each of the longitudinal portions 34, so as to guide the oil longitudinally flowing along the waveform of the longitudinal portion 34 in an up and down manner.

In addition, the square waveform structure of each of the guiding elements 33 form two opposite transverse openings 35 at the upper side 31 of the embossed plate 30 and two opposite transverse openings 35 at the bottom side 32 of the embossed plate 30. Therefore, the oil is guided to flow at the transverse openings 35 at both the upper and bottom sides 31, 32 of the embossed plate 30 in a transverse direction, i.e. the y-axis of the embossed plate 30.

Each of the waveform of the longitudinal portions 34 of the embossed plate 30 are preferably shifted with respect to an adjacent waveform of the longitudinal portion 34. Therefore, when the oil exits one of the transverse openings 35, the oil is then guided to longitudinally flow to another neighboring guiding element 33 along the longitudinal portion 34. Therefore, the oil is guided to transversely passing through the transverse openings 35, so as to create a three-dimensional guiding channel for the oil passing through the respective oil passageway 13.

More specifically, since each of the guiding elements 33 has two opposite transverse openings 35 located at the upper side 31 and bottom side 32 of the embossed plate 30, when the oil is passing through the oil passageway 13, the oil is being guided to flow at the transverse direction of the oil passageway 13, so as to flow therewithin in a three dimensional coordinates, which are conveniently defined as X, Y, and Z coordinates perpendicular to each other. For the sake of convenience, the X coordinate is defined as the longitudinal direction of the oil passageway 13, the Y coordinate is defined as the transverse direction, and the Z coordinate is defined as an up and down direction along the height of the oil passageway 13.

As a result, the each of the transverse openings 35 of the guiding element 33 is misaligned with the transverse opening 35 of the adjacent guiding element 33 at the adjacent longitudinal portion 34 of the embossed plate 30, so as to ensure the oil being guided to flow transversely along the Y coordinate from one transverse opening 35 to another transverse opening 35 while being guided to flow longitudinally along the X coordinate from one end to the other end of the embossed plate 30.

On the other hand, the longitudinal portion 34 having the wavy longitudinal cross section of each of the longitudinal portions 34 is preferably formed via a plurality of waves 36 repeatedly and continuously to form the continuously waveform structure of the longitudinal portion 34, wherein a configuration of each of the waves 36 has a crest 361 at the upper side 31 and a trough 362 at the bottom side 32 of the embossed plate 30, in such a manner that the continuously formed waves 36 are able to guide the oil passing through the embossed plate 30 in the up and down direction, so as to create the movement of the oil in the direction of Z coordinate. Accordingly, the embossed plate 30 is able to guide the oil flowing within the oil passageway 13 in directions of X, Y, and Z coordinates to create the three dimensional oil movements.

According to the preferred embodiment of the present invention, each of the guiding elements 33 is also formed by each of the waves 36 to alternatively protrude at the upper side 31 and the bottom side 32 of the embossed plate 30 to guide the oil passing through the oil passageway 13 in the three dimensional manner. As a result, the guiding element 33 has the crest 361 formed at the upper side 31 and the trough 362 formed at the bottom side 32, wherein the crest 361 is preferably contacting with an upper wall and bottom wall of the oil passageway 13, such that the guiding element 33 is able to ensure the oil being guided through the transverse openings 35 to effectively generate the three dimensional oil movement.

As will be readily appreciated by one skilled in the art, the three dimensional oil movement is able to well mix the oil within the oil passageways 13, so that the temperature of the oil therewithin is able to be relatively more evenly distributed and to prolong the heat exchanging time between the oil and the air, so as to effectively enhance the heat exchanging efficiency.

It is worth to mention that a height of each of the guiding elements 33 is preferably matching with a height of the corresponding oil passageways 13, so that the crest 361 and the trough 362 of each of the guiding elements 33 is contacting with the upper and bottom walls of the respective oil passageway 13, so as to effectively guide the oil passing through the guiding elements 33.

As mentioned above, the crest 361 and trough 362 of the guiding elements 33 preferably has a practically flat surface to increase the contacting area between a top flat surface of the crest 361 and the upper wall of the oil passageway 13 and a bottom flat surface of the trough 362 and the bottom wall of the oil passageway 13, so as to further ensure the oil is guided to flow through the transverse openings 35 of the embossed plate 30.

In other words, the guiding elements 33 continuously forming at the longitudinal portions 34 have practically and continuously trapezoid shape to define the top and bottom flat surfaces at each of the crests 361 and the troughs 362 of the waves 36 respectively. Therefore, the oil is ensured to be guided flow through the transverse openings 35 of the guiding elements 33. It is worth mentioning that each of the trapezoid shaped waves 36 can provide a relatively larger transverse opening 35 between the crest 361 and the trough 362 to prevent any residue of the oil being stuck at the guiding element 30 so as to block the movement of the oil within the oil passageway 13.

Each of the guiding elements 33 also has first and second edges defining at each of the top flat surface and the bottom flat surface thereof, wherein the first edge of the guiding elements 33 is connected to the second edge of the adjacent guiding elements 33 to form a plurality of transverse common lines 37 at the upper side 31 and the bottom side 32 of the embossed, in such a manner that the longitudinal portions 34 are connecting with the adjacent longitudinal portions 34 to form the shifted longitudinal portion 34 with respect to the adjacent longitudinal portions 34. It is appreciated that the first edge is preferably aligning and integrating with the second edge of the adjacent guiding elements 33 to form the transverse common lines 37, so that strength of the connection between any adjacent longitudinal portions 34 are enhanced, so as to reinforce the strength of the embossed plate 30.

According to the preferred embodiment of the present invention, the embossed plate 30 is preferably made of metal having higher heat transfer coefficient and higher temperature resistance. For example, the embossed plate 30 may be made of aluminum, which provides relatively higher heat transfer efficiency and the characteristic of lighter weight for minimizing the overall weight of oil cooler.

The guiding elements 33 protruding at the upper and bottom sides 31, 32 of the embossed plates 30 are preferably formed by a stamping compressive process, so as to integrally form the longitudinal portions 34 thereat. More specifically, the embossed plate 30 may be stamping pressed to form the guiding elements 33 thereat by forging a piece of metal. It will be appreciated that the guiding elements 33 may have other geographical shapes for creating the three-dimensional oil movement within the oil passageways 13. The guiding elements 33 in the present invention are integrally formed at the embossed plate 30 by integrally forming the longitudinal portions 34, so that the structure and the process of making the embossed plate 30 is simplified, so as to cost down the manufacturing cost.

FIG. 4 illustrates an alternative mode of the embossed plate 30, wherein the structural configuration is the same as it is mentioned above such as each of the embossed plates 30 has the upper side 31, the bottom side 32, and the guiding elements 33 protruding at the upper side 31 and the bottom side 32 in an alternating manner to guide the oil flowing between the upper side 31 and the bottom side 32 via the guiding elements 33. Instead of configuring each of the longitudinal portions 34 of the embossed plate 30 as a continuously square waveform structure, the longitudinal portion 34 of the embossed plate 30 can also be configured as continuously triangular waveform structure as shown in FIG. 4. It is appreciated that longitudinal portion 34 of the embossed plate 30 can also be configured as continuously sine waveform structure that the crest 361 and the trough 362 of each wave 36 has a curved configuration.

Referring to FIGS. 1 and 3 of the drawings, the oil guiding arrangement 10 further comprises one or more tubular oil tunnels 14, embodied as two tubular oil tunnels, a first tubular oil tunnels 141 to define the oil inlet 11 and communicatively connecting to the oil passageways 13, and a second tubular oil tunnels 142 to define the oil outlet 12 and communicatively connecting to the oil passageways 13 and the oil inlet 11. Therefore, the oil is guided to enter from the oil inlet 11 to the oil outlet 12 through the oil passageways 13.

More specifically, the oil passageways 13 are preferably formed by a plurality of oil guiding plates 15, in which the oil guiding plates 15 are longitudinally and communicatively extended between the two oil tunnels 14 for guiding the oil flowing through the oil passageways 13. Each of the oil passageways 13 are preferably formed by a pair of the oil guiding plates 15 overlapping with each other to sandwich and seal the embossed plate 30 therebetween, so that the oil is guided to pass through the embossed plates 30 within the oil passageways 13 in the three dimensional oil movement.

Each of the guiding plates 15 preferably has a central indented portion and a peripheral raised portion, so that a pair of the longitudinal oil guiding plates 15 are face-to-face overlapped with each other via the peripheral raised portions to define the oil passageways 13 within the central indented portions of the pair of the oil guiding plates 15, so as to contact the crest 361 of the guiding elements 30 with the top wall of the central portion and to contact the trough 362 of the guiding elements 30 with the bottom wall of the other central portion of the pair of oil guiding plates 15.

The guiding plate 15 further has at least one raised opening preferably located at one end of the longitudinal oil guiding plates 15 and protruded opposite to the raised peripheral portion, so that when the pairs of the oil guiding plates 15 are arranged to spacedly stack apart from each other, the raised opening are selectively communicating with the tubular oil tunnels 14 to guide the oil through the oil passageways 13. The oil inlet 11 is preferably defined at one of the tubular oil tunnels 14, while the oil outlet 12 is preferably defined at the other tubular oil tunnel 14, so that the oil is entered into the respective oil tunnel 14 to flow into the oil passageways 13 through the respective raised openings of the oil guiding plates 15.

The air guiding passageways 21 are preferably to be spacedly and alternatively stacked between two pairs of the oil guiding plates 15, and arranged to guide the air of the medium flow therethrough for heat exchange with the oil. A plurality of corrugated fins 22 are preferably located between the pairs of the oil guiding plates 15 being sandwiched therebetween, wherein each of the corrugated fins 22 is extended between two ends of the pair of oil guiding plates 15 and in contact with the respective central indented portions of the oil guiding plates 15, in such a manner that the heat exchanging area between the oil and the air is effectively increased, so as to enhance the efficiency of the oil cooler.

In this preferred embodiment of the present invention, the oil is guided to flow within the vertically spaced apart oil passageways 13 in a countercurrent flow manner, such that the oil is passing through the oil passageways in a zigzag configuration. Therefore, the oil flowing within the oil passageway 13 has an opposite flowing direction to the adjacent oil passageways 13. It is worth to mention that the flowing configurations of the oil are depended on the application of the oil cooler. The oil may be guided to flow within the oil passageway 13 in a concurrent manner.

One skilled in the art will understand that the embodiment of the present invention as shown in the drawings and described above is exemplary only and not intended to be limiting.

It will thus be seen that the objects of the present invention have been fully and effectively accomplished. It embodiments have been shown and described for the purposes of illustrating the functional and structural principles of the present invention and is subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims. 

1. An oil cooler for cooling oil, comprising: an oil guiding arrangement having an oil inlet, an oil outlet, and a plurality of oil passageways communicatively between said oil inlet and said outlet for guiding oil longitudinally flowing from said oil inlet to said oil outlet, wherein said oil passageways are spacedly stacked apart from each other; an air guiding arrangement having a plurality of air guiding passageways alternating with said oil passageways and arranged for guiding air flowing through said air guiding passageways to heat exchange with said oil so as to cool down said oil before exiting at said oil outlet; and a plurality of embossed plates disposed in said oil passageways respectively, wherein each of said embossed plates has an upper side, a bottom side, and a plurality of guiding elements protruding from said upper and bottom sides in an alternating manner in such a manner that when said oil flow passes through said oil passageway, said oil flow is guided to flow between said upper side and said bottom side, to transversely flow at said embossed plate, and to longitudinally flow at said embossed plate from said oil inlet to said oil outlet, so as to create a three-dimensional oil movement within said oil passageway to heat exchange with said air.
 2. The oil cooler, as recited in claim 1, wherein each of said embossed plates has a plurality of longitudinal portions that said guiding elements are alignedly formed along each of said longitudinal portions in a continuously square waveform structure, such that each of said longitudinal portions forms with a wavy longitudinal cross section at said embossed plate.
 3. The oil cooler, as recited in claim 2, wherein a waveform of said longitudinal portion is shifted with respect to a waveform of said adjacent longitudinal portion to create a three-dimensional guiding channel for said oil passing through said respective oil passageway.
 4. The oil cooler, as recited in claim 1, wherein each of said guiding elements has two opposite transverse openings at each of said upper and bottom sides for guiding said oil flowing at a transverse direction.
 5. The oil cooler, as recited in claim 2, wherein each of said guiding elements has two opposite transverse openings at each of said upper and bottom sides for guiding said oil flowing at a transverse direction.
 6. The oil cooler, as recited in claim 3, wherein each of said guiding elements has two opposite transverse openings at each of said upper and bottom sides for guiding said oil flowing at a transverse direction.
 7. The oil cooler, as recited in claim 4, wherein each of said transverse openings of said guiding element is misaligned with said transverse opening of said adjacent guiding element for ensuring said oil being guided to flow from one transverse opening to another transverse opening in three-dimensional oil movement.
 8. The oil cooler, as recited in claim 5, wherein each of said transverse openings of said guiding element is misaligned with said transverse opening of said adjacent guiding element for ensuring said oil being guided to flow from one transverse opening to another transverse opening in three-dimensional oil movement.
 9. The oil cooler, as recited in claim 6, wherein each of said transverse openings of said guiding element is misaligned with said transverse opening of said adjacent guiding element for ensuring said oil being guided to flow from one transverse opening to another transverse opening in three-dimensional oil movement.
 10. The oil cooler, as recited in claim 1, wherein a height of each of said guiding elements matches with a height of said corresponding oil passageways that crest and trough of each of said guiding elements contact with upper and bottom walls of said oil passageways to ensure said oil flowing in three-dimensional oil movement.
 11. The oil cooler, as recited in claim 6, wherein a height of each of said guiding elements matches with a height of said corresponding oil passageways that crest and trough of each of said guiding elements contact with upper and bottom walls of said oil passageways to ensure said oil flowing in three-dimensional oil movement.
 12. The oil cooler, as recited in claim 9, wherein a height of each of said guiding elements matches with a height of said corresponding oil passageways that crest and trough of each of said guiding elements contact with upper and bottom walls of said oil passageways to ensure said oil flowing in three-dimensional oil movement.
 13. The oil cooler, as recited in claim 10, wherein each of said guiding elements has a trapezoid shape defining a top flat surface at said crest contacting with said upper wall of said oil passageway and a bottom flat surface at said trough contacting with said bottom wall of said oil passageway.
 14. The oil cooler, as recited in claim 11, wherein each of said guiding elements has a trapezoid shape defining a top flat surface at said crest contacting with said upper wall of said oil passageway and a bottom flat surface at said trough contacting with said bottom wall of said oil passageway.
 15. The oil cooler, as recited in claim 12, wherein each of said guiding elements has a trapezoid shape defining a top flat surface at said crest contacting with said upper wall of said oil passageway and a bottom flat surface at said trough contacting with said bottom wall of said oil passageway.
 16. The oil cooler, as recited in claim 13, wherein each of said guiding elements has first and second edges defining at each of said top and bottom flat surfaces, wherein said first edge of each of said guiding elements is aligned and integrated with said second edge of said adjacent guiding element to form a transverse common line so as to reinforce a strength of said embossed plate.
 17. The oil cooler, as recited in claim 14, wherein each of said guiding elements has first and second edges defining at each of said top and bottom flat surfaces, wherein said first edge of each of said guiding elements is aligned and integrated with said second edge of said adjacent guiding element to form a transverse common line so as to reinforce a strength of said embossed plate.
 18. The oil cooler, as recited in claim 15, wherein each of said guiding elements has first and second edges defining at each of said top and bottom flat surfaces, wherein said first edge of each of said guiding elements is aligned and integrated with said second edge of said adjacent guiding element to form a transverse common line so as to reinforce a strength of said embossed plate.
 19. The oil cooler, as recited in claim 1, wherein each of said embossed plates is stamping pressed to form said guiding elements thereat by forging a piece of metal plate.
 20. The oil cooler, as recited in claim 9, wherein each of said embossed plates is stamping pressed to form said guiding elements thereat by forging a piece of metal plate.
 21. The oil cooler, as recited in claim 15, wherein each of said embossed plates is stamping pressed to form said guiding elements thereat by forging a piece of metal plate.
 22. The oil cooler, as recited in claim 1, wherein said oil guiding arrangement comprises two tubular oil tunnels defining said oil inlet and said oil outlet thereat respectively, and a plurality of oil guiding plates which are longitudinally extended between said oil tunnels and are overlapped and sealed in pairs to form said oil passageway therebetween.
 23. The oil cooler, as recited in claim 21, wherein said oil guiding arrangement comprises two tubular oil tunnels defining said oil inlet and said oil outlet thereat respectively, and a plurality of oil guiding plates which are longitudinally extended between said oil tunnels and are overlapped and sealed in pairs to form said oil passageway therebetween.
 24. The oil cooler, as recited in claim 22, wherein said air guiding arrangement comprises a plurality of corrugated fins disposed within said air guiding passageways respectively at a position that each of said corrugated fins is sandwiched between two pairs of said oil guiding plates.
 25. The oil cooler, as recited in claim 23, wherein said air guiding arrangement comprises a plurality of corrugated fins disposed within said air guiding passageways respectively at a position that each of said corrugated fins is sandwiched between two pairs of said oil guiding plates. 